Almost all of the system seller games have yet to release on the Wii U and it's still sold over 6mil. The gc had better support earlier on. When the nukes drop, the Wii U is going to soar passed the gc imo.

Very well then.

I will split this up into two different groups: A: Those who know Wii U exists and B: Those who don't understand what Wii U is

A: This group is made up of the Nintendo fans and the gamers that pay attention to game related news. Firstly, I believe that there are still a good amount of Nintendo fans who haven't bought the Wii U yet. Why? The 3DS. I know that people don't think Consoles & HH's cross but they do for the general fanbase. All you have to do is look at past generations to know that a lot of Nintendo HH and console owners overlap. A Nintendo faithful is likely to get both...eventually. The 3DS is $170, the XL is $200, and Wii U $300. Nintendo fans will just stick with their 3DS until either the price drops to a level there happy with or more importantly, a game from there favorite series is released. As for the core gamer, (truthfully, there isn't THAT many) some will buy it as a second console once the price gets low enough. ($200 maybe?) The Wii U might be missing out on a ton of games but the Wii U is slowly building a solid library. This will help sales later on.

B: This group is made up of the average consumer, families, and kids. Marketing for the Wii U has been terrible and I doubt many understand what the Wii U is. They might have heard of it before but they don't care about it because they aren't convinced that it's any different than a Wii. For the price of $300 they can get a...??? This is where Nintendo needs to step it up besides just making great games. By increasing the marketing budget (esspecially during the Holidays) and releasing GamePad focused games (NFC) They could get people interested. 

Overall, the Wii U currently only has platforming and party games. Once this changes and they get a wider & more impressive library, the Nintendo fans will come. 

At this time, the GC was $150 and had a much better and broader library of games. This comparable September, the GC dropped to just $100. The Wii U is still the most expensive Nintendo console ever (even adjusted for inflation) going into its 2nd full year. Nintendo systems normally peak earlier on but I expect Wii U to have more longevity, esspecially compared to GC.

WiiU has had 2D and 3D mario, Wii series, Zelda (remake) which did wonders for Wii I recall? and Donkey Kong. Yet almost all of the system sellers have yet to release?

Smash, Mario Kart and Zelda. What else?

I knew this was a Wii U thread before entering here.

Yes because there are more customers and people interested in video games now but it won't sell much more than gamecube

Nope, Nintendo will get a successor out in 2016, and I don't see any way the WiIU will close the gap by then.

Yeah this argument that the WiiU has no real system sellers yet never made any sense. NSMB sold nearly 30m units on the Wii AND the DS. How is that not a system seller? Mario Galaxy sold over 11m last gen, do 3D Mario games not count as system sellers anymore? Donkey Kong sold 6m on the Wii, that's a very popular franchise that's doing nothing for the WiiU. The problem has always been with the console.

This.. (very good statet)

Yeah, they can absolutely still pass the Gamecube, at least marginally.
If they fix their awful branding and marketing, somehow getting consumers interested in a piece of software that feels unique on the gamepad, and cut the recommended bundled with a game price to $250 soon.

Let's go through your list:

2D Mario, 3D Mario, Donkey Kong - All platformers

Wii Series: We both know nobody is going to pay $300 to play Wii Party or Wii Fit in HD. Wii Sports Club is digital-only which basically means it doesn't exist to its target audience.

Zelda WWHD: Yes, an HD remake of a Zelda is going to sell Wii U's by the dozen. Let's ignore the fact that it happens to be from the GC too.

I believe every decent-sized game can be a system seller in regards to being the breaking point for someone to want a system. With that said, look at the list you gave. Let's explore this more and see the other exclusives on Wii U. (We know multi plats sell like poop on it)

2012: Nintendo Land & Sing Party (Party Games) ZombiU

2013: NSLU, Game & Wario, Mario & Sonic ATOG, Sonic Lost World (Look more party and platform games!) Lego City, Pikmin 3, TW101

2014: Nothing you haven't listed as of April (As said, DK was yet another platformer)

So, what does the Wii U library consist of? Platformers and party games. Besides that we have 3 niche games in ZombiU, Pikmin 3, and TW101. Then we are left with Lego City, a game also released on 3DS. (Them 4 games can't sell to not platform fans by themselves)

As you can see, Wii U's library is lacking terribly in variety. Unless you love platformers, you don't want a Wii U. (For the most part)